charset=utf8 results in empty input

I'm using trpc-openapi and some of our customers are using Zapier to communicate with it.

Zapier uses the header

Content-Type: application/json; charset=utf-8

Content-Type: application/json; charset=utf-8

Content-Type: application/json; charset=utf-8

Content-Type: application/json; charset=utf-8 - note the additional

charset=utf-8

charset=utf-8

charset=utf-8

charset=utf-8

When

charset=utf-8

charset=utf-8

charset=utf-8

charset=utf-8 exists, the input to the relevant procedure is

{}

{}

{}

{}

Has anybody encountered this? Is there a way to support it?